370 lines
14 KiB
Nix
370 lines
14 KiB
Nix
{ config, lib, pkgs, ... }:
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with lib;
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let
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cfg = config.services.syncoid;
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# Extract local dasaset names (so no datasets containing "@")
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localDatasetName = d: optionals (d != null) (
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let m = builtins.match "([^/@]+[^@]*)" d; in
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optionals (m != null) m
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);
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# Escape as required by: https://www.freedesktop.org/software/systemd/man/systemd.unit.html
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escapeUnitName = name:
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lib.concatMapStrings (s: if lib.isList s then "-" else s)
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(builtins.split "[^a-zA-Z0-9_.\\-]+" name);
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# Function to build "zfs allow" and "zfs unallow" commands for the
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# filesystems we've delegated permissions to.
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buildAllowCommand = zfsAction: permissions: dataset: lib.escapeShellArgs [
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# Here we explicitly use the booted system to guarantee the stable API needed by ZFS
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"-+/run/booted-system/sw/bin/zfs"
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zfsAction
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cfg.user
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(concatStringsSep "," permissions)
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dataset
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];
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in
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{
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# Interface
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options.services.syncoid = {
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enable = mkEnableOption "Syncoid ZFS synchronization service";
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interval = mkOption {
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type = types.str;
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default = "hourly";
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example = "*-*-* *:15:00";
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description = ''
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Run syncoid at this interval. The default is to run hourly.
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The format is described in
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<citerefentry><refentrytitle>systemd.time</refentrytitle>
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<manvolnum>7</manvolnum></citerefentry>.
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'';
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};
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user = mkOption {
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type = types.str;
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default = "syncoid";
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example = "backup";
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description = ''
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The user for the service. ZFS privilege delegation will be
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automatically configured for any local pools used by syncoid if this
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option is set to a user other than root. The user will be given the
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"hold" and "send" privileges on any pool that has datasets being sent
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and the "create", "mount", "receive", and "rollback" privileges on
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any pool that has datasets being received.
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'';
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};
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group = mkOption {
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type = types.str;
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default = "syncoid";
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example = "backup";
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description = "The group for the service.";
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};
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sshKey = mkOption {
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type = types.nullOr types.path;
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# Prevent key from being copied to store
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apply = mapNullable toString;
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default = null;
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description = ''
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SSH private key file to use to login to the remote system. Can be
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overridden in individual commands.
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'';
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};
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localSourceAllow = mkOption {
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type = types.listOf types.str;
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# Permissions snapshot and destroy are in case --no-sync-snap is not used
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default = [ "bookmark" "hold" "send" "snapshot" "destroy" ];
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description = ''
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Permissions granted for the <option>services.syncoid.user</option> user
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for local source datasets. See
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<link xlink:href="https://openzfs.github.io/openzfs-docs/man/8/zfs-allow.8.html"/>
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for available permissions.
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'';
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};
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localTargetAllow = mkOption {
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type = types.listOf types.str;
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default = [ "change-key" "compression" "create" "mount" "mountpoint" "receive" "rollback" ];
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example = [ "create" "mount" "receive" "rollback" ];
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description = ''
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Permissions granted for the <option>services.syncoid.user</option> user
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for local target datasets. See
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<link xlink:href="https://openzfs.github.io/openzfs-docs/man/8/zfs-allow.8.html"/>
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for available permissions.
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Make sure to include the <literal>change-key</literal> permission if you send raw encrypted datasets,
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the <literal>compression</literal> permission if you send raw compressed datasets, and so on.
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For remote target datasets you'll have to set your remote user permissions by yourself.
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'';
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};
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commonArgs = mkOption {
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type = types.listOf types.str;
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default = [ ];
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example = [ "--no-sync-snap" ];
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description = ''
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Arguments to add to every syncoid command, unless disabled for that
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command. See
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<link xlink:href="https://github.com/jimsalterjrs/sanoid/#syncoid-command-line-options"/>
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for available options.
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'';
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};
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service = mkOption {
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type = types.attrs;
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default = { };
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description = ''
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Systemd configuration common to all syncoid services.
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'';
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};
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commands = mkOption {
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type = types.attrsOf (types.submodule ({ name, ... }: {
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options = {
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source = mkOption {
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type = types.str;
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example = "pool/dataset";
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description = ''
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Source ZFS dataset. Can be either local or remote. Defaults to
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the attribute name.
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'';
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};
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target = mkOption {
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type = types.str;
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example = "user@server:pool/dataset";
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description = ''
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Target ZFS dataset. Can be either local
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(<replaceable>pool/dataset</replaceable>) or remote
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(<replaceable>user@server:pool/dataset</replaceable>).
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'';
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};
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recursive = mkEnableOption ''the transfer of child datasets'';
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sshKey = mkOption {
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type = types.nullOr types.path;
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# Prevent key from being copied to store
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apply = mapNullable toString;
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description = ''
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SSH private key file to use to login to the remote system.
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Defaults to <option>services.syncoid.sshKey</option> option.
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'';
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};
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localSourceAllow = mkOption {
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type = types.listOf types.str;
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description = ''
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Permissions granted for the <option>services.syncoid.user</option> user
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for local source datasets. See
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<link xlink:href="https://openzfs.github.io/openzfs-docs/man/8/zfs-allow.8.html"/>
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for available permissions.
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Defaults to <option>services.syncoid.localSourceAllow</option> option.
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'';
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};
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localTargetAllow = mkOption {
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type = types.listOf types.str;
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description = ''
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Permissions granted for the <option>services.syncoid.user</option> user
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for local target datasets. See
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<link xlink:href="https://openzfs.github.io/openzfs-docs/man/8/zfs-allow.8.html"/>
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for available permissions.
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Make sure to include the <literal>change-key</literal> permission if you send raw encrypted datasets,
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the <literal>compression</literal> permission if you send raw compressed datasets, and so on.
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For remote target datasets you'll have to set your remote user permissions by yourself.
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'';
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};
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sendOptions = mkOption {
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type = types.separatedString " ";
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default = "";
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example = "Lc e";
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description = ''
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Advanced options to pass to zfs send. Options are specified
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without their leading dashes and separated by spaces.
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'';
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};
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recvOptions = mkOption {
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type = types.separatedString " ";
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default = "";
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example = "ux recordsize o compression=lz4";
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description = ''
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Advanced options to pass to zfs recv. Options are specified
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without their leading dashes and separated by spaces.
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'';
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};
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useCommonArgs = mkOption {
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type = types.bool;
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default = true;
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description = ''
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Whether to add the configured common arguments to this command.
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'';
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};
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service = mkOption {
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type = types.attrs;
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default = { };
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description = ''
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Systemd configuration specific to this syncoid service.
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'';
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};
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extraArgs = mkOption {
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type = types.listOf types.str;
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default = [ ];
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example = [ "--sshport 2222" ];
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description = "Extra syncoid arguments for this command.";
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};
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};
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config = {
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source = mkDefault name;
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sshKey = mkDefault cfg.sshKey;
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localSourceAllow = mkDefault cfg.localSourceAllow;
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localTargetAllow = mkDefault cfg.localTargetAllow;
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};
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}));
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default = { };
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example = literalExample ''
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{
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"pool/test".target = "root@target:pool/test";
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}
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'';
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description = "Syncoid commands to run.";
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};
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};
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# Implementation
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config = mkIf cfg.enable {
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users = {
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users = mkIf (cfg.user == "syncoid") {
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syncoid = {
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group = cfg.group;
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isSystemUser = true;
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# For syncoid to be able to create /var/lib/syncoid/.ssh/
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# and to use custom ssh_config or known_hosts.
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home = "/var/lib/syncoid";
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createHome = false;
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};
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};
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groups = mkIf (cfg.group == "syncoid") {
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syncoid = { };
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};
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};
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systemd.services = mapAttrs'
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(name: c:
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nameValuePair "syncoid-${escapeUnitName name}" (mkMerge [
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{
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description = "Syncoid ZFS synchronization from ${c.source} to ${c.target}";
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after = [ "zfs.target" ];
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startAt = cfg.interval;
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# syncoid may need zpool to get feature@extensible_dataset
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path = [ "/run/booted-system/sw/bin/" ];
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serviceConfig = {
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ExecStartPre =
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(map (buildAllowCommand "allow" c.localSourceAllow) (localDatasetName c.source)) ++
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(map (buildAllowCommand "allow" c.localTargetAllow) (localDatasetName c.target));
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ExecStopPost =
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(map (buildAllowCommand "unallow" c.localSourceAllow) (localDatasetName c.source)) ++
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(map (buildAllowCommand "unallow" c.localTargetAllow) (localDatasetName c.target));
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ExecStart = lib.escapeShellArgs ([ "${pkgs.sanoid}/bin/syncoid" ]
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++ optionals c.useCommonArgs cfg.commonArgs
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++ optional c.recursive "-r"
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++ optionals (c.sshKey != null) [ "--sshkey" c.sshKey ]
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++ c.extraArgs
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++ [
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"--sendoptions"
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c.sendOptions
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"--recvoptions"
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c.recvOptions
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"--no-privilege-elevation"
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c.source
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c.target
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]);
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User = cfg.user;
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Group = cfg.group;
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StateDirectory = [ "syncoid" ];
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StateDirectoryMode = "700";
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# Prevent SSH control sockets of different syncoid services from interfering
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PrivateTmp = true;
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# Permissive access to /proc because syncoid
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# calls ps(1) to detect ongoing `zfs receive`.
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ProcSubset = "all";
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ProtectProc = "default";
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# The following options are only for optimizing:
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# systemd-analyze security | grep syncoid-'*'
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AmbientCapabilities = "";
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CapabilityBoundingSet = "";
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DeviceAllow = [ "/dev/zfs" ];
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LockPersonality = true;
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MemoryDenyWriteExecute = true;
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NoNewPrivileges = true;
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PrivateDevices = true;
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PrivateMounts = true;
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PrivateNetwork = mkDefault false;
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PrivateUsers = true;
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ProtectClock = true;
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ProtectControlGroups = true;
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ProtectHome = true;
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ProtectHostname = true;
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ProtectKernelLogs = true;
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ProtectKernelModules = true;
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ProtectKernelTunables = true;
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ProtectSystem = "strict";
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RemoveIPC = true;
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RestrictAddressFamilies = [ "AF_UNIX" "AF_INET" "AF_INET6" ];
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RestrictNamespaces = true;
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RestrictRealtime = true;
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RestrictSUIDSGID = true;
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RootDirectory = "/run/syncoid/${escapeUnitName name}";
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RootDirectoryStartOnly = true;
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BindPaths = [ "/dev/zfs" ];
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BindReadOnlyPaths = [ builtins.storeDir "/etc" "/run" "/bin/sh" ];
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# Avoid useless mounting of RootDirectory= in the own RootDirectory= of ExecStart='s mount namespace.
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InaccessiblePaths = [ "-+/run/syncoid/${escapeUnitName name}" ];
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MountAPIVFS = true;
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# Create RootDirectory= in the host's mount namespace.
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RuntimeDirectory = [ "syncoid/${escapeUnitName name}" ];
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RuntimeDirectoryMode = "700";
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SystemCallFilter = [
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"@system-service"
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# Groups in @system-service which do not contain a syscall listed by:
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# perf stat -x, 2>perf.log -e 'syscalls:sys_enter_*' syncoid …
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# awk >perf.syscalls -F "," '$1 > 0 {sub("syscalls:sys_enter_","",$3); print $3}' perf.log
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# systemd-analyze syscall-filter | grep -v -e '#' | sed -e ':loop; /^[^ ]/N; s/\n //; t loop' | grep $(printf ' -e \\<%s\\>' $(cat perf.syscalls)) | cut -f 1 -d ' '
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"~@aio"
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"~@chown"
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"~@keyring"
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"~@memlock"
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"~@privileged"
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"~@resources"
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"~@setuid"
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"~@timer"
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];
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SystemCallArchitectures = "native";
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# This is for BindPaths= and BindReadOnlyPaths=
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# to allow traversal of directories they create in RootDirectory=.
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UMask = "0066";
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};
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}
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cfg.service
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c.service
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]))
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cfg.commands;
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};
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meta.maintainers = with maintainers; [ julm lopsided98 ];
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}
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